Analytical energy gradients of a self-consistent reaction-field solvation model based on CM2 atomic charges

Analytical energy gradients have been derived for an SM5-type solvation mod el based on Hartree-Fock self-consistent reaction-field theory and CM2 atom ic charges. The method is combined with an analytic treatment of the first derivatives of nonelectrostatic first-solvation-shell contributions to the free energy and implemented in the General Atomic and Molecular Electronic Structure System (GAMESS). The resulting equations allow one to use accurat e class IV charges to calculate equilibrium geometries of solutes in liquid -phase solutions. The algorithm is illustrated by calculations of optimized geometries and solvation free energies for water, methanol, dimethyl disul fide, and 9-methyladenine in water and 1-octanol. (C) 1999 American Institu te of Physics. [S0021-9606(99)30311-1].